For semiconductor devices, for example power semiconductor devices, compound semiconductors such as III-V compound semiconductors have become more and more important in recent years, since they allow for semiconductor devices with higher doping and shorter drift zone compared to silicon-based semiconductor devices while retaining a high blocking capability.
Up to now, power semiconductor devices based on III-V compound semiconductors are realized as lateral devices. These devices are known as high electron mobility transistors (HEMTs). A HEMT includes several layers of differently doped semiconducting materials with different band gaps. Due to the different band gaps of the individual layers, a two-dimensional electron gas (2DEG) is formed at the interface of these layers, the two-dimensional electron gas serving as a conductive channel. The mobility of the electrons as well as the 2D-electron charge carrier density is very high in two-dimensional electron gas.
The two-dimensional electron gas is provided in a region between a source electrode and a drain electrode. When the HEMT is reverse-biased, breakdown occurs in a region between a gate electrode and the drain electrode and the two-dimensional electron gas is significantly deteriorated by hot charge carriers.
For these and other reasons there is a need for the present invention.